Editor's note: This is the first in a two-part series on celebrities taking notice of political and global issues.

George Clooney on the Darfur crisis. Angelina Jolie on AIDS funding. Eva Longoria on illegal immigrants’ rights.

Some big-screen actors are doing considerably more lately than just dropping money in the charity bucket. A select group of celebrities is becoming expert on big issues and joining politicians on immigration, poverty and other causes.

But are they helping?

Celebrities “bring attention and reporters to a cause that wouldn’t otherwise happen,” said James Hirsen, author of Hollywood Nation and a columnist for NewsMax.com.

More celebrities have jumped into the political fray in recent years than decades ago when they took a more back seat to politics. Hirsen said celebrities are stretching their wings more today than in yesteryear because the old Hollywood system prevented stars from speaking about issues or stepping out of movie studios' rules.

"It used to be abnormal," Hirsen said. But with the added responsibility, stars have realized that to use their power effectively for a cause means they have to know the details of their causes.

Angelina Jolie "may not understand the problems with the U.N. but she seems to have a pretty good understanding of her role as ambassador," Hirsen said.

But others say getting behind the cause célèbre is just a matter of stars being gluttons for attention.

“We’re seeing a merger of celebrities and politics,” said Peter Schweizer, author of Do As I Say, (Not As I Do), Profiles in Liberal Hypocrisy. “I think they crave the spotlight. They also crave to be taken seriously.

“I think people see through it," Schweizer said

It's a big deal on Capitol Hill when a celebrity makes an appearance at a congressional hearing or press conference. Lawmakers win the privilege of having a famous name associated to their causes, and reporters and television cameras flock to provide coverage.

Cameras were ready to catch a shot of Jessica Simpson when she lobbied Congress in March about funding for Operation Smile, a non-profit group that provides plastic surgery for disadvantaged children overseas suffering from facial deformities. More recently, Susan Sarandon joined New York Sen. Hillary Clinton to promote the late Christopher Reeve’s battle for spinal cord research.

While donations and appearances have been the norm for a while, Clooney’s trip to Darfur, Jolie’s global travels to help underprivileged children worldwide and Longoria's interest in aiding Hispanic immigrants to gain more labor rights and access to health care highlight recent efforts to take the extra step at getting involved.

Clooney recently visited the nation's capital to boost support for and draw attention to the crisis in Darfur. He said he wants to see more funding for peacekeeping and humanitarian aid to the region.

Joined by Clooney, Sens. Barack Obama, D-Ill, and Sam Brownback, R-Kan., held an event on Darfur at the National Press Club late last month. The press conference drew a packed house of camera crews and reporters. A few days later at an event minus Clooney, few cameras showed up to hear about the plight of the Sudanese.

”Clooney obviously brings a profile and star power that brings attention to whatever issue he’s talking about,” said Tommy Vietor, a spokesman for Obama. “He knows a lot about what’s going on in the Sudan and what needs to be done.”

In the same week, Clooney also spoke out at a rally on the National Mall and made appearances on morning television and cable news to explain what he learned during a trip to the region.

“It changes you forever, obviously,” Clooney told FOX News. “For me, I just have never been around that kind of cruelty. I have never seen it in my life.”

Georgette Mosbacher, a Republican fundraiser, said while she credits celebrities like Clooney for educating themselves on global matters, she questions the motivation behind it.

“I definitely give [Clooney] credit for his involvement. He has brought it to the forefront,” Mosbacher said of the crisis in Darfur. “I think the only issue I have is whether it’s more than just a photo op, and are they truly engaged in the issue?”

Robert Zimmerman, a Democratic strategist, said Clooney has helped make Darfur a national issue.

“I think where George Clooney — or people like Bono, who played a significant role in Africa, or Robert Redford on the environment — has been in terms of galvanizing Congress to pay close attention to issues and also mobilizing the country to demand action,” Zimmerman said. “I’m proud of George Clooney’s attention to the issue.”

But Mosbacher said while Clooney has made the Darfur story more noticeable to the general public, Washington, D.C., has not been absent on the matter, and the Bush administration has paid considerable attention to the issue.

“I wouldn’t say that they galvanized the American public. We have been there and we will continue to be,” Mosbacher said.

At least some celebrity watchers say they don't think the attention to detail will last, and the celebrity bandwagon is just a matter of how long stars can hold their focus on a subject.

“It helps celebrities live in a world of fantasy and emotion,” said Hirsen.